This invention relates to a catheter stem that reduces the volume of embolic material, which may be knocked loose from an artery all or the wall of a chamber of the heart as a result of a medical procedure, from entering a selected oxygenated blood carrying artery system. More specifically, the invention relates to a catheter for isolating and perfusing a segment of a patient""s cardiovascular system and for directing circulatory flow around the isolated segment. More particularly, it relates to an apparatus for deployment within a patient""s aortic arch and to methods for selectively perfusing the arch vessels with a fluid, while directing blood flow within the aortic lumen past the isolated arch vessels.
In the field of cardiovascular surgery, it has been common practice for surgeons to perform a sternotomy to expose the body cavity in the thorax region, wherein retractors are employed to provide the necessary access to internal structures to perform the necessary medical procedures.
Depending on the medical procedure to be performed, it has often been necessary to arrest heart activity for some period of time during the procedure. The blood is then diverted through a cardiopulmonary bypass pump in order to maintain sufficient oxygenated blood flow to the body. Procedures performed as described above cause significant trauma to the body due to the method of entry into the thorax region, and the cessation of heart activity. Recent trends in the development of surgical devices have been toward the use of less invasive techniques, so that operations cause less extensive trauma. Furthermore, there has been a trend toward reducing the amount of time the heart is stopped, or eliminating the step of stopping the heart.
One major disadvantage to any procedure performed on the heart or on major arteries associated with the heart, even for less invasive procedures, is that embolic material may be knocked loose from arterial walls, heart valves, or from the interior walls of the chambers of the heart, and pumped to the brain, where the resulting blockages may cause neurological damage.
Cardiopulmonary bypass pumps are frequently used to pump blood in the patient while the heart is stopped during surgery, and bypass pumps generally include a filter mechanism to trap embolic material from the blood before the oxygenated blood is returned to the body. However, when the heart is started embolic material from within the heart may be pumped to the brain. Aortic perfusion shunts, as described in common owned and copending U.S. patent application, Ser. No. 09/212,580, filed Dec. 15, 1998, claiming the benefit of provisional application, Ser. No. 60/069,470, filed Dec. 15, 1997, hereby incorporated in its entirety, have been developed that allow the blood from the heart to perfuse the body, while providing separate perfusion of the arch vessels. The aortic perfusion shunts described represent a significant step forward in protection against cerebral embolization, however, there remains a tremendous need for further improvements in devices and methods for protecting a patient against the potential of cerebral embolization.
What is needed is a catheter device for se in minimally invasive medical procedures and for standard open chest surgery that is simple and relatively inexpensive and that is capable of isolating the circulation of the arch vessels, while still allowing the heart to perform the function of perfusing the body of the patient.
Accordingly, the invention is a catheter with a fluid flow control member called a deflector or a fluid flow divider positioned near the distal end of the catheter for dividing a first lumen into two channels near a point where a second lumen branches from the first lumen, and for perfusing the branch lumen. The invention will be described more specifically herein relating to an aortic catheter having a divider positioned in the aortic arch proximate the arch vessels.
The flow divider may be formed in a variety of configurations. In general the flow divider will have an undeployed or collapsed state and an expanded or deployed state. The flow divider may be deployed from an exterior surface of the catheter shaft, or it may be deployed from within a lumen in the catheter shaft. In embodiments wherein the flow divider is coupled to an exterior surface, the flow divider will preferably have an undeployed state wherein the flow divider is contained in a relatively small volume around the circumference of the distal end (nearest the heart) of the catheter, having an exterior circumference that is preferably not significantly larger than the exterior circumference of the catheter. In embodiments wherein the flow divider is deployed from within the catheter, the flow divider preferably has an undeployed state that is sized and configured for storage within a lumen in the catheter. In both configurations, the catheter will generally have a deployed state in which the length and width of the flow divider is sufficient to divide blood flow in the aorta in the vicinity of the ostia of the arch vessels.
The flow divider may comprise one or more inflatable chambers or one or more selectively deployable shrouds. The inflatable chambers may be relatively non-compliant or they may be compliant, exhibiting elastic behavior after initial inflation to closely fit the aortic lumen size and curvature.
The catheter may further include one or more additional or auxiliary flow control members located upstream or downstream from the flow divider to further segment the patient""s circulatory system for selective perfusion to different organ systems within the body or to assist in anchoring the catheter in a desired position. These auxiliary flow control members may comprise inflatable balloons or selectively deployable external catheter valves. The anchoring members may be inflatable balloons or other anchoring structures that provide sufficient force or friction to prevent the catheter from drifting from a selected position within the aorta.
In a preferred embodiment, the catheter shaft includes at least three lumens, one lumen for inflating or otherwise deploying the flow divider, a second for perfusion of the arch vessels, and a third guidewire lumen. In alternate embodiments, additional lumens may be included for deploying the auxiliary flow control members, and for measuring the pressure at desired locations within the aorta. The catheter may be configured for retrograde deployment via a peripheral artery, such as the femoral artery, or it may be configured for antegrade deployment via an aortotomy incision or direct puncture in the ascending aorta.
Methods according to the present invention are described using the aortic catheter for occluding and compartmentalizing or partitioning the patient""s aortic lumen and for performing selective filtered aortic perfusion.